?? decode.c
字號:
#include <math.h>
#include <stdlib.h>
#include "common.h"
#include "decode.h"
#include "huffman.h"
void decode_info(Bit_stream_struc *bs, frame_params *fr_ps)
{
layer *hdr = fr_ps->header;
hdr->version = get1bit(bs);
hdr->lay = 4-getbits(bs,2);
hdr->error_protection = !get1bit(bs); /* 錯誤保護. TRUE/FALSE */
hdr->bitrate_index = getbits(bs,4);
hdr->sampling_frequency = getbits(bs,2);
hdr->padding = get1bit(bs);
hdr->extension = get1bit(bs);
hdr->mode = getbits(bs,2);
hdr->mode_ext = getbits(bs,2);
hdr->copyright = get1bit(bs);
hdr->original = get1bit(bs);
hdr->emphasis = getbits(bs,2);
}
void III_get_side_info(Bit_stream_struc *bs, III_side_info_t *si, frame_params *fr_ps)
{
int ch, gr, i;
int stereo = fr_ps->stereo;
si->main_data_begin = getbits(bs, 9);
if (stereo == 1)
si->private_bits = getbits(bs,5);
else
si->private_bits = getbits(bs,3);
for (ch=0; ch<stereo; ch++)
for (i=0; i<4; i++)
si->ch[ch].scfsi[i] = get1bit(bs);
for (gr=0; gr<2; gr++) {
for (ch=0; ch<stereo; ch++) {
si->ch[ch].gr[gr].part2_3_length = getbits(bs, 12);
si->ch[ch].gr[gr].big_values = getbits(bs, 9);
si->ch[ch].gr[gr].global_gain = getbits(bs, 8);
si->ch[ch].gr[gr].scalefac_compress = getbits(bs, 4);
si->ch[ch].gr[gr].window_switching_flag = get1bit(bs);
if (si->ch[ch].gr[gr].window_switching_flag) {
si->ch[ch].gr[gr].block_type = getbits(bs, 2);
si->ch[ch].gr[gr].mixed_block_flag = get1bit(bs);
for (i=0; i<2; i++)
si->ch[ch].gr[gr].table_select[i] = getbits(bs, 5);
for (i=0; i<3; i++)
si->ch[ch].gr[gr].subblock_gain[i] = getbits(bs, 3);
/* Set region_count parameters since they are implicit in this case. */
if (si->ch[ch].gr[gr].block_type == 0) {
printf("Side info bad: block_type == 0 in split block.\n");
exit(0);
}
else if (si->ch[ch].gr[gr].block_type == 2
&& si->ch[ch].gr[gr].mixed_block_flag == 0)
si->ch[ch].gr[gr].region0_count = 8; /* MI 9; */
else si->ch[ch].gr[gr].region0_count = 7; /* MI 8; */
si->ch[ch].gr[gr].region1_count = 20 - si->ch[ch].gr[gr].region0_count;
}
else {
for (i=0; i<3; i++)
si->ch[ch].gr[gr].table_select[i] = getbits(bs, 5);
si->ch[ch].gr[gr].region0_count = getbits(bs, 4);
si->ch[ch].gr[gr].region1_count = getbits(bs, 3);
si->ch[ch].gr[gr].block_type = 0;
}
si->ch[ch].gr[gr].preflag = get1bit(bs);
si->ch[ch].gr[gr].scalefac_scale = get1bit(bs);
si->ch[ch].gr[gr].count1table_select = get1bit(bs);
}
}
}
struct {
int l[5];
int s[3];
} sfbtable = {
{0, 6, 11, 16, 21},
{0, 6, 12}
};
int slen[2][16]={
{0, 0, 0, 0, 3, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4},
{0, 1, 2, 3, 0, 1, 2, 3, 1, 2, 3, 1, 2, 3, 2, 3}
};
struct {
int l[23];
int s[14];
} sfBandIndex[3]= {
{{0,4,8,12,16,20,24,30,36,44,52,62,74,90,110,134,162,196,238,288,342,418,576},
{0,4,8,12,16,22,30,40,52,66,84,106,136,192}},
{{0,4,8,12,16,20,24,30,36,42,50,60,72,88,106,128,156,190,230,276,330,384,576},
{0,4,8,12,16,22,28,38,50,64,80,100,126,192}},
{{0,4,8,12,16,20,24,30,36,44,54,66,82,102,126,156,194,240,296,364,448,550,576},
{0,4,8,12,16,22,30,42,58,78,104,138,180,192}}
};
void III_get_scale_factors(III_scalefac_t *scalefac, III_side_info_t *si, int gr, int ch, frame_params *fr_ps)
{
int sfb, i, window;
struct gr_info_s *gr_info = &(si->ch[ch].gr[gr]);
if (gr_info->window_switching_flag && (gr_info->block_type == 2)) {
if (gr_info->mixed_block_flag) { /* MIXED */ /* NEW - ag 11/25 */
for (sfb = 0; sfb < 8; sfb++)
(*scalefac)[ch].l[sfb] = hgetbits(
slen[0][gr_info->scalefac_compress]);
for (sfb = 3; sfb < 6; sfb++)
for (window=0; window<3; window++)
(*scalefac)[ch].s[window][sfb] = hgetbits(
slen[0][gr_info->scalefac_compress]);
for (sfb = 6; sfb < 12; sfb++)
for (window=0; window<3; window++)
(*scalefac)[ch].s[window][sfb] = hgetbits(
slen[1][gr_info->scalefac_compress]);
for (sfb=12,window=0; window<3; window++)
(*scalefac)[ch].s[window][sfb] = 0;
}
else { /* SHORT*/
for (i=0; i<2; i++)
for (sfb = sfbtable.s[i]; sfb < sfbtable.s[i+1]; sfb++)
for (window=0; window<3; window++)
(*scalefac)[ch].s[window][sfb] = hgetbits(
slen[i][gr_info->scalefac_compress]);
for (sfb=12,window=0; window<3; window++)
(*scalefac)[ch].s[window][sfb] = 0;
}
}
else { /* LONG types 0,1,3 */
for (i=0; i<4; i++) {
if ((si->ch[ch].scfsi[i] == 0) || (gr == 0))
for (sfb = sfbtable.l[i]; sfb < sfbtable.l[i+1]; sfb++)
(*scalefac)[ch].l[sfb] = hgetbits(
slen[(i<2)?0:1][gr_info->scalefac_compress]);
}
(*scalefac)[ch].l[22] = 0;
}
}
/* 已經(jīng)在 huffman.c中聲明
struct huffcodetab ht[HTN];
*/
int huffman_initialized = FALSE;
void initialize_huffman()
{
FILE *fi;
if (huffman_initialized) return;
if (!(fi = OpenTableFile("huffdec.txt") )) {
printf("Please check huffman table 'huffdec.txt'\n");
exit(1);
}
if (fi==NULL) {
fprintf(stderr,"decoder table open error\n");
exit(3);
}
if (read_decoder_table(fi) != HTN) {
fprintf(stderr,"decoder table read error\n");
exit(4);
}
huffman_initialized = TRUE;
}
void III_hufman_decode(long int is[SBLIMIT][SSLIMIT], III_side_info_t *si, int ch, int gr, int part2_start, frame_params *fr_ps)
{
int i, x, y;
int v, w;
struct huffcodetab *h;
int region1Start;
int region2Start;
int bt = (*si).ch[ch].gr[gr].window_switching_flag && ((*si).ch[ch].gr[gr].block_type == 2);
initialize_huffman();
/* 查找區(qū)域邊界 */
if ( ((*si).ch[ch].gr[gr].window_switching_flag) &&
((*si).ch[ch].gr[gr].block_type == 2) ) {
/* Region2. */
region1Start = 36; /* sfb[9/3]*3=36 */
region2Start = 576; /* No Region2 for short block case. */
}
else { /* 查找長塊情況下的區(qū)域邊界. */
region1Start = sfBandIndex[fr_ps->header->sampling_frequency]
.l[(*si).ch[ch].gr[gr].region0_count + 1]; /* MI */
region2Start = sfBandIndex[fr_ps->header->sampling_frequency]
.l[(*si).ch[ch].gr[gr].region0_count +
(*si).ch[ch].gr[gr].region1_count + 2]; /* MI */
}
/* 讀取大值區(qū)域Read bigvalues area. */
for (i=0; i<(*si).ch[ch].gr[gr].big_values*2; i+=2) {
if (i<region1Start) h = &ht[(*si).ch[ch].gr[gr].table_select[0]];
else if (i<region2Start) h = &ht[(*si).ch[ch].gr[gr].table_select[1]];
else h = &ht[(*si).ch[ch].gr[gr].table_select[2]];
huffman_decoder(h, &x, &y, &v, &w);
is[i/SSLIMIT][i%SSLIMIT] = x;
is[(i+1)/SSLIMIT][(i+1)%SSLIMIT] = y;
}
/* Read count1 area. */
h = &ht[(*si).ch[ch].gr[gr].count1table_select+32];
while ((hsstell() < part2_start + (*si).ch[ch].gr[gr].part2_3_length ) &&
( i < SSLIMIT*SBLIMIT )) {
huffman_decoder(h, &x, &y, &v, &w);
is[i/SSLIMIT][i%SSLIMIT] = v;
is[(i+1)/SSLIMIT][(i+1)%SSLIMIT] = w;
is[(i+2)/SSLIMIT][(i+2)%SSLIMIT] = x;
is[(i+3)/SSLIMIT][(i+3)%SSLIMIT] = y;
i += 4;
}
if (hsstell() > part2_start + (*si).ch[ch].gr[gr].part2_3_length)
{ i -=4;
rewindNbits(hsstell()-part2_start - (*si).ch[ch].gr[gr].part2_3_length);
}
/* Dismiss stuffing Bits */
if ( hsstell() < part2_start + (*si).ch[ch].gr[gr].part2_3_length )
hgetbits( part2_start + (*si).ch[ch].gr[gr].part2_3_length - hsstell());
/* Zero out rest. */
for (; i<SSLIMIT*SBLIMIT; i++)
is[i/SSLIMIT][i%SSLIMIT] = 0;
}
int pretab[22] = {0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,2,2,3,3,3,2,0};
void III_dequantize_sample(long int is[SBLIMIT][SSLIMIT], double xr[SBLIMIT][SSLIMIT], III_scalefac_t *scalefac, struct gr_info_s *gr_info, int ch, frame_params *fr_ps)
{
int ss,sb,cb=0,sfreq=fr_ps->header->sampling_frequency;
int stereo = fr_ps->stereo;
int next_cb_boundary, cb_begin, cb_width, sign;
/* choose correct scalefactor band per block type, initalize boundary */
if (gr_info->window_switching_flag && (gr_info->block_type == 2) )
if (gr_info->mixed_block_flag)
next_cb_boundary=sfBandIndex[sfreq].l[1]; /* LONG blocks: 0,1,3 */
else {
next_cb_boundary=sfBandIndex[sfreq].s[1]*3; /* pure SHORT block */
cb_width = sfBandIndex[sfreq].s[1];
cb_begin = 0;
}
else
next_cb_boundary=sfBandIndex[sfreq].l[1]; /* LONG blocks: 0,1,3 */
/* apply formula per block type */
for (sb=0 ; sb < SBLIMIT ; sb++) {
for (ss=0 ; ss < SSLIMIT ; ss++) {
if ( (sb*18)+ss == next_cb_boundary) { /* Adjust critical band boundary */
if (gr_info->window_switching_flag && (gr_info->block_type == 2)) {
if (gr_info->mixed_block_flag) {
if (((sb*18)+ss) == sfBandIndex[sfreq].l[8]) {
next_cb_boundary=sfBandIndex[sfreq].s[4]*3;
cb = 3;
cb_width = sfBandIndex[sfreq].s[cb+1] -
sfBandIndex[sfreq].s[cb];
cb_begin = sfBandIndex[sfreq].s[cb]*3;
}
else if (((sb*18)+ss) < sfBandIndex[sfreq].l[8])
next_cb_boundary = sfBandIndex[sfreq].l[(++cb)+1];
else {
next_cb_boundary = sfBandIndex[sfreq].s[(++cb)+1]*3;
cb_width = sfBandIndex[sfreq].s[cb+1] -
sfBandIndex[sfreq].s[cb];
cb_begin = sfBandIndex[sfreq].s[cb]*3;
}
}
else {
next_cb_boundary = sfBandIndex[sfreq].s[(++cb)+1]*3;
cb_width = sfBandIndex[sfreq].s[cb+1] -
sfBandIndex[sfreq].s[cb];
cb_begin = sfBandIndex[sfreq].s[cb]*3;
}
}
else /* long blocks */
next_cb_boundary = sfBandIndex[sfreq].l[(++cb)+1];
}
/* Compute overall (global) scaling. */
xr[sb][ss] = pow( 2.0 , (0.25 * (gr_info->global_gain - 210.0)));
/* Do long/short dependent scaling operations. */
if (gr_info->window_switching_flag && (
((gr_info->block_type == 2) && (gr_info->mixed_block_flag == 0)) ||
((gr_info->block_type == 2) && gr_info->mixed_block_flag && (sb >= 2)) )) {
xr[sb][ss] *= pow(2.0, 0.25 * -8.0 *
gr_info->subblock_gain[(((sb*18)+ss) - cb_begin)/cb_width]);
xr[sb][ss] *= pow(2.0, 0.25 * -2.0 * (1.0+gr_info->scalefac_scale)
* (*scalefac)[ch].s[(((sb*18)+ss) - cb_begin)/cb_width][cb]);
}
else { /* LONG block types 0,1,3 & 1st 2 subbands of switched blocks */
xr[sb][ss] *= pow(2.0, -0.5 * (1.0+gr_info->scalefac_scale)
* ((*scalefac)[ch].l[cb]
+ gr_info->preflag * pretab[cb]));
}
/* Scale quantized value. */
sign = (is[sb][ss]<0) ? 1 : 0;
xr[sb][ss] *= pow( (double) abs(is[sb][ss]), ((double)4.0/3.0) );
if (sign) xr[sb][ss] = -xr[sb][ss];
}
}
}
void III_reorder(double xr[SBLIMIT][SSLIMIT], double ro[SBLIMIT][SSLIMIT], struct gr_info_s *gr_info, frame_params *fr_ps)
{
int sfreq=fr_ps->header->sampling_frequency;
int sfb, sfb_start, sfb_lines;
int sb, ss, window, freq, src_line, des_line;
for(sb=0;sb<SBLIMIT;sb++)
for(ss=0;ss<SSLIMIT;ss++)
ro[sb][ss] = 0;
if (gr_info->window_switching_flag && (gr_info->block_type == 2)) {
if (gr_info->mixed_block_flag) {
/* NO REORDER FOR LOW 2 SUBBANDS */
for (sb=0 ; sb < 2 ; sb++)
for (ss=0 ; ss < SSLIMIT ; ss++) {
ro[sb][ss] = xr[sb][ss];
}
/* REORDERING FOR REST SWITCHED SHORT */
for(sfb=3,sfb_start=sfBandIndex[sfreq].s[3],
sfb_lines=sfBandIndex[sfreq].s[4] - sfb_start;
sfb < 13; sfb++,sfb_start=sfBandIndex[sfreq].s[sfb],
(sfb_lines=sfBandIndex[sfreq].s[sfb+1] - sfb_start))
for(window=0; window<3; window++)
for(freq=0;freq<sfb_lines;freq++) {
src_line = sfb_start*3 + window*sfb_lines + freq;
des_line = (sfb_start*3) + window + (freq*3);
ro[des_line/SSLIMIT][des_line%SSLIMIT] =
xr[src_line/SSLIMIT][src_line%SSLIMIT];
}
}
else { /* pure short */
for(sfb=0,sfb_start=0,sfb_lines=sfBandIndex[sfreq].s[1];
sfb < 13; sfb++,sfb_start=sfBandIndex[sfreq].s[sfb],
(sfb_lines=sfBandIndex[sfreq].s[sfb+1] - sfb_start))
for(window=0; window<3; window++)
for(freq=0;freq<sfb_lines;freq++) {
src_line = sfb_start*3 + window*sfb_lines + freq;
des_line = (sfb_start*3) + window + (freq*3);
ro[des_line/SSLIMIT][des_line%SSLIMIT] =
xr[src_line/SSLIMIT][src_line%SSLIMIT];
}
}
}
else { /*long blocks */
for (sb=0 ; sb < SBLIMIT ; sb++)
for (ss=0 ; ss < SSLIMIT ; ss++)
ro[sb][ss] = xr[sb][ss];
}
}
void III_stereo(double xr[2][SBLIMIT][SSLIMIT], double lr[2][SBLIMIT][SSLIMIT], III_scalefac_t *scalefac, struct gr_info_s *gr_info, frame_params *fr_ps)
{
int sfreq = fr_ps->header->sampling_frequency;
int stereo = fr_ps->stereo;
int ms_stereo = (fr_ps->header->mode == MPG_MD_JOINT_STEREO) &&
(fr_ps->header->mode_ext & 0x2);
int i_stereo = (fr_ps->header->mode == MPG_MD_JOINT_STEREO) &&
(fr_ps->header->mode_ext & 0x1);
int sfb;
int i,j,sb,ss,ch,is_pos[576];
double is_ratio[576];
/* intialization */
for ( i=0; i<576; i++ )
is_pos[i] = 7;
if ((stereo == 2) && i_stereo )
{ if (gr_info->window_switching_flag && (gr_info->block_type == 2))
{ if( gr_info->mixed_block_flag )
{ int max_sfb = 0;
for ( j=0; j<3; j++ )
{ int sfbcnt;
sfbcnt = 2;
for( sfb=12; sfb >=3; sfb-- )
{ int lines;
lines = sfBandIndex[sfreq].s[sfb+1]-sfBandIndex[sfreq].s[sfb];
i = 3*sfBandIndex[sfreq].s[sfb] + (j+1) * lines - 1;
while ( lines > 0 )
{ if ( xr[1][i/SSLIMIT][i%SSLIMIT] != 0.0 )
{ sfbcnt = sfb;
sfb = -10;
lines = -10;
}
lines--;
i--;
}
}
sfb = sfbcnt + 1;
if ( sfb > max_sfb )
max_sfb = sfb;
while( sfb<12 )
{ sb = sfBandIndex[sfreq].s[sfb+1]-sfBandIndex[sfreq].s[sfb];
i = 3*sfBandIndex[sfreq].s[sfb] + j * sb;
for ( ; sb > 0; sb--)
{ is_pos[i] = (*scalefac)[1].s[j][sfb];
if ( is_pos[i] != 7 )
is_ratio[i] = tan( is_pos[i] * (PI / 12));
i++;
}
sfb++;
}
sb = sfBandIndex[sfreq].s[11]-sfBandIndex[sfreq].s[10];
sfb = 3*sfBandIndex[sfreq].s[10] + j * sb;
sb = sfBandIndex[sfreq].s[12]-sfBandIndex[sfreq].s[11];
i = 3*sfBandIndex[sfreq].s[11] + j * sb;
for ( ; sb > 0; sb-- )
{ is_pos[i] = is_pos[sfb];
is_ratio[i] = is_ratio[sfb];
i++;
}
}
if ( max_sfb <= 3 )
{ i = 2;
ss = 17;
sb = -1;
while ( i >= 0 )
{ if ( xr[1][i][ss] != 0.0 )
{ sb = i*18+ss;
i = -1;
} else
{ ss--;
if ( ss < 0 )
{ i--;
ss = 17;
}
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